Species composition, population dynamics, and assessment of biopesticide application on thrips (Thysanoptera) in Sacred lotus Nelumbo nucifera Gaertn.

Abstract

Species composition and population dynamics of thrips in sacred lotus, Nelumbo nucifera Gaertn, were examined in natural and cultivated areas. The results indicated that three species of thrips (Scirtothrips dorsalis Hood, Selenothrips rubrocinctus (Giard) and Frankliniella schultzei (Trybom)) were present on various parts of the plant. S. dorsalis had the widest niche breadth; it was the predominant species and was more abundant in cultivated area than in natural areas. The abundance was related to seasonal variations and farmer’s practices. Three biopesticides, namely wood vinegar, azadiractin, and the entomopathogenic fungus Beauvaria bassiana, were experimentally found to reduce S. dorsalis on lotus. The efficiency against S. dorsalis of imidacloprid was not significantly different from that of wood vinegar. The value of Shannon-Wiener diversity index was lower than in the other treatments, but Simpson’s index indicated that diversity of the aquatic organism after wood vinegar treatment was highest. Although the efficiency of biopesticides and chemical control did not differ much, from biodiversity perspective the biopesticides are easily biodegradable and do not cause resistance build-up among the pests. Therefore, biopesticides, such as wood vinegar, are alternative methods for thrip control in sacred lotus.

Keywords

• scirtothrips dorsalis
• selenothrips rubrocinctus
• frankliniella schultzei
• niche
• wood vinegar